Map of Westdean No.3 showing geology and water level contours. (Click to enlarge)

Hydrogeological setting

Thin head deposits (chalky, sandy and silty clay, locally pebbly) overlie the Seaford Chalk Formation at the site. The well is located in a dry valley on the eastern side of the Cuckmere valley. The well is at the lower end of its catchment, and water levels are only slightly above mean sea level.

Well or borehole construction

The borehole was drilled to 24.99 m in 1896 and water levels have been measured since 1904. It was plumbed as being 21.1 m deep (21.5 m below top of lining tubes) in 1972. Neither the drilled diameter of the borehole nor the length of the casing are known.

Hydrograph response

The Chalk is unconfined and the hydrograph has an annual sinusoidal appearance. The hydrograph exhibits a relatively flashy response, probably because of the relatively small size of the associated chalk blocks. Levels regress consistently to around 1.5 metres above sea level, normally peaking between 2.5 and 3.5 meters above sea level, but with occasional peaks above 4 meters, which may be considered indicative of localised groundwater flooding in the catchment.

Data issues

No data are available for 1971 (due to bees' nest in recorder) or 1972.